Analysis of slow interdomain motion of macromolecules using NMR relaxation data
Analysis of slow interdomain motion of macromolecules using NMR relaxation data
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DOI：
10.1021/ja0041876
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发表时间：
2001-05-02
影响因子：
15
通讯作者：
Tjandra, N
中科院分区：
文献类型：
--
作者：
Baber, JL;Szabo, A;Tjandra, N
被认为是具有慢畴间运动的大分子的NMR弛豫数据的解释。它示出了如何“扩展的无模型方法”可以用来分析在三个不同的磁场强度爪蟾钙离子连接钙调蛋白获得的N-15骨架松弛数据。这种蛋白质由两个结构域组成，这两个结构域由两个刚性螺旋连接，刚性螺旋由柔性片段连接。它是可能的，唯一地确定所有的“扩展无模型”参数，而没有任何先验的假设，关于它们的大小，同时最小二乘拟合的弛豫数据在两个不同的磁场测量。据发现，两个连接的螺旋（因此域）经历相对于其中两个螺旋是平行的构象的缓慢运动。这些“摆动”运动的时间尺度和幅度的特征在于有效的相关时间和平方阶参数约为3纳秒和0.7，分别。这些值是一致的独立估计表明，该程序提供了一个有用的一阶描述复杂的内部运动的大分子，尽管忽略了整体和域间运动的耦合。
The interpretation of NMR relaxation data for macromolecules possessing slow interdomain motions is considered. It is shown how the "extended model-free approach" can be used to analyze N-15 backbone relaxation data acquired at three different field strengths for Xenopus Ca2+-ligated calmodulin. This protein is comprised of two domains connected by two rigid helices joined by a flexible segment. It is possible to uniquely determine all "extended model-free" parameters without any a priori assumptions regarding their magnitudes by simultaneously least-squares fitting the relaxation data measured at two different magnetic fields. It is found that the two connecting helices (and consequently the domains) undergo slow motions relative to the conformation in which the two helices are parallel. The time scales and amplitudes of these "wobbling" motions are characterized by effective correlation times and squared-order parameters of approximately 3 ns and 0.7, respectively. These values are consistent with independent estimates indicating that this procedure provides a useful first-order description of complex internal motions in macromolecules despite neglecting the coupling of overall and interdomain motions.